Vibration analysis of electric rotating machines has been conducted for decades, but most of the standard methods have involved monitoring the external components of the machine to ascertain problems caused from internal movement in the machine. However, recent developments have seen proximity probes and accelerometers being used on internal components of the machine to measure the bearing and shaft vibration in electric rotating machines in an effort to monitor the mechanical condition of the machines. Although, most proximity probes in use provide static measurements when the electric rotating machine is not in operation; thus, requiring shut down to monitor of the machine condition.
In electric rotating machines the stator windings are insulated to prevent electrical discharge and for efficient machine operation. The stator winding insulation is exposed to harsh operating conditions, such as high temperatures for example. A slow but steady exposure to multiple stresses, such as voltage stress, mechanical forces, and thermal effects, during the operation of the machine bring about a change in the nature of the insulation. Degradation of the insulation brought about by these multiple stresses result in vibration of the stator windings, which in turn lead to further degradation of the stator windings. The vibration subsequently leads to increased partial electrical discharge in the stator windings and finally to machine failure. Without insulation, the conducting stator windings come in contact with each other or with the grounded stator core, causing the current to flow in undesired paths and thereby preventing the proper operation of the machine. Thus, it is imperative to detect such early vibrations during the operation of the machine and take corrective actions else degradation of the insulation may lead to irreversible damage.
Accordingly, there is need for methods and systems for monitoring stator winding vibrations, for example, to detect and dynamically monitor early vibrations during the operation of the electric rotating machine.